Unitized bonnet assemblies have heretofore been provided for hydrants but in such prior constructions there has always been a part or element of the operating mechanism of the unitized bonnet assembly which is exposed to the water system which necessitates such part or member being made of a non-corrosive expensive material. Further, in such prior arrangements, when it was necessary to remove the unitized bonnet assembly from the hydrant barrel, it was sometimes necessary to break the joint between the valve stem and the element of the bonnet member to which it was attached since such joint was exposed to the waterway and resulted in corrosion between the stem and the element. In other such unitized bonnet assemblies, the removal of the unitized bonnet assembly resulted in loss of lubricant such as oil or the like from the lubricant reservoir and, additionally, these types of unitized bonnet assemblies required the lubricant reservoir to be filled after assembly. Additionally, the connection of these type of unitized bonnet assemblies to the valve stem was such that the torsional loads applied by the operating nut in opening and closing the hydrant valve was transferred through the valve stem to the valve element and to the valve seat. This resulted in the valve seat having to be installed with higher torques. In arrangements where the torque of the operating nut was absorbed in the bonnet, the element absorbing such torque was exposed to the water system thus necessitating it being manufactured from an expensive non-corrosive material.
Such prior constructions are disclosed in the copending United States application of Lawrence F. Luckenbill, Ser. No. 733,853, filed Oct. 19, 1976 now U.S. Pat. No. 4,083,377 and assigned to the same assignee as this application, namely Mueller Co., of Decatur, Ill. Likwise, such prior constructions are shown in the U.S. Pat. No. 3,223,110, issued Dec. 14, 1964, to Frank H. Mueller and John J. Smith and also assigned to the same assignee, Mueller Co., of Decatur, Ill.